Competitive reaction pathways in the addition of phenylacetylene to diamidonaphthalene-bridged diiridium complexes

Citation
Mv. Jimenez et al., Competitive reaction pathways in the addition of phenylacetylene to diamidonaphthalene-bridged diiridium complexes, ORGANOMETAL, 18(7), 1999, pp. 1125-1136
Citations number
57
Categorie Soggetti
Organic Chemistry/Polymer Science
Journal title
ORGANOMETALLICS
ISSN journal
02767333 → ACNP
Volume
18
Issue
7
Year of publication
1999
Pages
1125 - 1136
Database
ISI
SICI code
0276-7333(19990329)18:7<1125:CRPITA>2.0.ZU;2-I
Abstract
The oxidative addition of phenylacetylene to the monohydrido diiridium comp lex [Ir-2(mu-1,8-(NH)(2)naphth)H(CO)(2)(PiPr(3))(2)] (CF3SO3) (2) and the d iiridium(II) species [Ir-2(mu-1,8-(NH)(2)-naphth)(CF3SO3)(2)(CO)(2)(PiPr(3) )(2)] (3) has been studied. The kinetic product of the addition to 2 is the dihydridoalkynyl complex [Ir-2(mu-1,8-(NH)(2)naphth)mu-C=CPh)H-2(CO)(2)(Pi Pr(3))(2)](CF3SO3) (4), in which the alkynyl ligand bridges the iridium ato ms in a mu,eta(1):eta(2)-coordination mode. Compound 4 isomerizes in aceton e solution tot give the hydride-bridged complex [Ir-2(mu-1,8-(NH)(2)naphth) (mu-H)H(C=CPh)(CO)(2)(PiPr(3))(2)](CF3SO3) (5), in which both the alkynyl a nd the terminal hydride ligands are in a trans position with respect to the bridging hydride. The reaction of phenylacetylene with 3 gives different k inetic products depending on the solvent used. In CH2Cl2, the diiridium(III ) derivative [Ir-2(mu-1,8-(NH)(2)naphth)H(C=CPh)(CO)(2)(PiPr(3))(2)](CF3SO3 )(2) (6) is obtained. On heating these CH2Cl2 solutions, 6 isomerizes into the vinylidene-bridged complex [Ir-2(mu-1,8-(NH)(2)naphth)mu-C=CHPh)(CF3SO3 )(2)(CO)(2)(PiPr(3))(2)]-(7), which has been characterized by X-ray diffrac tion. The triflate ligands of 7 can be substituted by acetonitrile ligands to give the dicationic compound [Ir-2(mu-1,8-(NH)(2)naphth)-(mu-C=CHPh)(NCC H3)(2)(CO)(2)(PiPr(3))(2)](CF3SO3)(2) (8). With acetone as the reaction sol vent, the addition of phenylacetylene to 3 affords deprotonated compounds o f formula [Ir-2(mu-1,8-(NH)(2)-naphth)(C=CPh)(CO)(2)(PiPr(3))(2)](CF3SO3) ( 9 and 10). The thermally stable isomer 10 can be protonated to give 7 but c an also react with an excess of phenylacetylene to give the neutral diiridi um(II) species [Ir-2(mu-1,8-(NH)(2)naphth)(C=CPh)(2)(CO)(2)(PiPr(3))(2)] (1 1), which is the isolable product of the reaction of 3 with an excess of ph enylacetylene in acetone. When this latter reaction is carried out in aceto ne/H2O as solvent, the acylalkynyl diiridium(II) complex [Ir-2(mu-1,8-(NH)( 2)naphth)(C=CPh)(C(O)CH2Ph)(CO)(2)(PiPr(3))(2)] (12) is the major reaction product. The molecular structure of 12 was determined by X-ray diffraction.